Car keys are shown next to a canister of medicinal cannabis, rolling papers, and whole and ground … [+]
2018 Toronto Star
Cannabis and cars, two of the country’s hottest topics, will always draw a crowd. But as long as confusion persists in the media about basic aspects of the plant, experts worry that public safety, policy and fairness, and general awareness around cannabis could be set back for years to come.
Because while all of us want safer roads (regardless of how we relax or medicate), misinformation and misunderstanding won’t get us there.
Case in point this week is a study by the American Automobile Association (AAA), which compared the number of pre- and post-cannabis legalization traffic deaths in Washington state wherein one or more drivers involved tested positive for THC, the most well-known psychoactive cannabinoid chemical, one of many such chemicals (intoxicating or not) that our bodies produce when we use cannabis.
Research by AAA’s Foundation for Traffic Safety found that, between 2008 and 2012, an estimated 8.8% of Washington drivers involved in fatal crashes tested positive for THC. In the years 2013 to 2017, after state legalization of adult-use cannabis in 2012, that rate rose to 18%, the group reported. “The average number of THC-positive drivers increased, too,” AAA wrote in a press release.
“In the five years before legalization, an average of 56 drivers involved in fatal crashes each year were THC-positive. In the five years after legalization, the average jumped to 130” — including all drivers involved in fatal crashes who later tested positive for THC, whether they survived, were killed, or also tested positive for other substances.
What these numbers tell us is that, during the five-year periods before and after state legalization, THC was found in the bodies of over twice as many people involved in fatal crashes in Washington during the latter period. Study data also showed that the methods and rates of drug-testing among Washington drivers involved in fatal accidents had fluctuated both before and after legalization.
What they don’t tell us, among other things, is whether any of those people were driving high. In fact, the AAA study itself pointed this out — and the fact that THC can be detected in the body long after the effects have worn off, from hours to months, depending on the test.
“THC levels in blood peak shortly after cannabis is smoked, and then they decline substantially by the time of peak impairment, which generally occurs approximately 90 minutes after consumption. Any acute impairing effects of THC typically subside within about 2-3.5 hours [of smoking],” AAA authors explained in their study.
“While occasional users of cannabis may no longer have detectable levels of THC in their blood by this time, frequent users may still have relatively high concentrations of THC in their blood well beyond the period of acute impairment.”
“In general, the presence of detectable THC in blood suggests, but does not conclusively prove, that a person has recently used cannabis,” they also noted. “THC blood levels and impairment are not well-correlated.”
Nor did AAA present data on whether traffic fatalities overall rose in Washington after cannabis legalization. Even with that data, it would be very difficult to determine whether legal cannabis is responsible for more road deaths, versus any number of other factors. But some media headlines and stories made the connection anyway.
The authors do cite another group’s study, “examining fatal crash rates in Washington and Colorado (where recreational cannabis use was also legalized in December 2012).” Those researchers estimated “an increase of 1.2 fatal crashes per billion vehicle miles traveled post-legalization relative to control states, and an increase of 1.8 fatal crashes per billion vehicle miles traveled after retail sales of cannabis began in 2014 relative to before legalization,” AAA authors wrote.
On request, AAA provided annual tallies of Washington state traffic fatalities overall during the years their study covered, which dipped from 521 in 2008 to a low of 436 2013 and climbed up to 563 by 2017. A spokesman for AAA commented in an email, “While the number of fatalities statewide did increase after legalization, we can’t definitively say that the increase was due to marijuana legalization.”
“Some of it may have been, but there was also an increasing trend in traffic fatalities nationwide over the same period, so we know that there were clearly other factors at play besides marijuana legalization,” he said.
Unlike most media coverage, the study also acknowledges that the increase in THC-linked traffic fatalities “was not immediate,” and seemingly “occurred gradually throughout 2013 before reaching a relatively stable post-[leglaization] level in 2014.”
“Data from 2015 through 2017 appear to be suggestive of a continued slight increasing trend in the proportion of fatal-crash-involved drivers who are THC positive, however, it is unclear at this point whether this is attributable to random fluctuation, uncertainty in the imputed values, or whether the proportion is continuing to trend upward,” authors wrote.
A parked driver lights a joint or marijuana cigarette while sitting in the driver’s seat in this … [+]
Toronto Star via Getty Images
For groups who focus on cannabis science or driving safety year round, the nuances of this kind of research may be easier to spot, as well as the need for accurate coverage and further study. As we pursue needed data on these issues, they may also disagree about how cannabis or other drugs may affect our road behaviors long term.
After decades of research, and close to 130 years of US automotive history, experts on road safety and human biology agree on one thing, though:
People shouldn’t drive impaired, for the sake of their own lives but especially those around them. Not when they’re impaired by alcohol, cannabis, cocaine, PCP, cough syrup, prescription meds, mescaline, excess caffeine, nor anything else that compromises their abilities to pilot heavy machinery at speed.
But at present, researchers still can’t say exactly how much of the most popular drugs will impair most drivers’ abilities (since every body handles drugs differently, and research is often still ongoing), so regulators who are charged with road safety use their best estimates in the meantime.
And while road-safety authorities say that totally drug-free driving is always your best bet, they also specifically acknowledge — unlike some recent media reports, and any number of previous ones — that having a detectable drug in your body doesn’t mean you are impaired, nor that you’re intoxicated or ‘high’ on it.
For example, most US states have outlawed driving with a blood-alcohol level that’s above the .05% to .08% range (about 1-2 drinks) — a.k.a. the line for being legally intoxicated — which is often lowered to 0.0% for younger and probationary drivers.
Even if drivers aren’t legally intoxicated or ‘over the line,’ police may still determine, based on drivers’ behavior and performance, that they are legally impaired.
For the sake of helping drivers and other US residents use drugs like cannabis and alcohol responsibly, it’s important for regulators and media outlets to convey that intoxication and impairment aren’t as cut-and-dry as some blood and urine tests — or road data — may seem to suggest.
Northwest regional radio program KIRO Nights co-host Aaron Mason commented in response to the study and its media coverage last week, “We really have to get out there and let people know that it’s not so simple — there’s a lot to it.”
For context, KIRO Nights also pointed out on their website, “In terms of vehicle fatalities involving alcohol, 30 percent of fatal crashes in Washington involved alcohol-impaired drivers in 2016, and 31 percent in 2017.”
Mason added to listeners, “But the thing to keep in mind: Do not operate a motor vehicle if you are not sober. If you’re drunk, you’re not sober, and if you’re high, you’re not sober.”